The Study On Determination Of Pyrethroid Pesticide Residues In Tilapia And Water Production Process

Tilapia is one of the important breeding and exporting fish in our country. The maximum residues limit of pesticide in pond water and aquatic product is increasingly more stringent as pyrethroid pesticides is widely used in fishery production.To break the trade barriers and expanding export of tilapia, the rapid determination of pyrethroid pesticides in pond water and aquatic product is necessary.30bottles of water samples and30tilapia samples were collected from five representative fisheries which were located in the suburb of Changsha. The main results were shown as follow:(1)Five kinds of pyrethroid pesticides, namely bifenthrin, fenpropathrin,cyhaloth rin,cypermethrin and deltamethrin in water were determined simultaneously by liquid-liquid extration (LLE) and gas chromatography with electron capture detector (GC-ECD). In this method, n-hexane was extraction solvent. The method was reliable and stable that the recoveries were from80.52%-91.59%at three spiked level, with the relative standard deviations ranging from3.47%to6.21%. In practical sample determination, no pesticide under test were detected from water samples which were collected from five fisheries.(2)Five kinds of pyrethroid pesticides, namely bifenthrin, fenpropathrin, cyhalothrin, cypermethrin and deltamethrin in tilapia were determined simultaneously by matrix solid-phase dispersion (MSPD) and gas chromatography with electron capture detector (GC-ECD). In this method acetonitrile was eluent, florisil was sorbent. The method was reliable and stable that the recoveries were from83.65%to98.66%at two spiked level10and20μg/kg, with the relative standard deviations ranging from3.17%to6.08%. In practical sample determination, cypermethrin were detected from all the tilapia samples which were collected from five fisheries.(3) For find out the main sources of measurement uncertainty in the data, which were about determination cypermethrin in tilapia by GC, the measurement uncertainty was analyzed by developing mathematic model and concluding mathematic expression of uncertainty in this measurement. Ultimately, the combined uncertainty and expanded uncertainty were determined. It was resulted that the measurement uncertainty mainly derives from the repeated measurements.